Composition of Bioactive Compounds from Potato Peel Waste Extracts by Decoction and Indirect Ultra-Sound Assisted Extraction Methods

Purpose: The aim of this study was to obtain potato peel extracts by a conventional, “decoction (DT)” and novel, “indirect ultra-sound assisted extraction (DuAE)” methods, and determine the composition of potato peel extracts in bioactive compounds. Materials and Methods: To obtain peels extracts, both DT and DuAE extraction methods were used to extract bioactive compounds from peel wastes of five potato cultivars i.e. Kinigi, Kuruseke, Kirundo, Peco, and T58, locally grown in Rwanda. Four types of bioactive compounds, i.e. glycolakaloids (TGC), total phenolics (TPC), total flavonoids (TFC), and total anthocyanins (TAC) were determined in each potato peel extract. Data in concentration of bioactive compounds was subjected to a two factor ANOVA (p ≤ 0.05) to determine the effect of potato cultivars and extraction methods on the content of bioactive compounds. Findings: Results showed that the composition ranges of bioactive compounds were 0.47- 11.83 mg SE/100g, 60.12 -1170.01 mg GAE/100g, 50.39- 873.26 mg QE/100g, and 0.71- 8.73 mg CGE/100 g per dry weight for TGC, TPC, TFC, and TAC, respectively. The composition of bioactive compounds in potato peel extracts was significantly (p<0.001) affected by both potato cultivar and extraction method. Generally, potato peel extracts from Kirundo and Kuruseke cultivars had the lowest and the highest amount of bioactive compounds, respectively; whereas the DuAE method performed better than DT method. Implications to Theory, Practice and Policy: Results from this study revealed the significant role of extraction methods used for bioactive compounds. An investigation on the optimization and improvement of extraction processes used in this study was recommended.